Merge pull request #5042 from luishendrix92/main

#30 - OCaml

Author: Roswell468

Roadmap/30 - SOLID DIP/ocaml/luishendrix92.ml

@@ -0,0 +1,173 @@
+open Printf
+
+(******************************************************************************)
+(*                                                                            *)
+(*                       Dependency Inversion Principle                       *)
+(*                                                                            *)
+(*  DIP is the strategy of depending upon interfaes or abstract functions     *)
+(*  and classes rather than upon concrete functions and classes. A good rule  *)
+(*  to apply is that higher-level components should not depend on a lower     *)
+(*  level component, and they should also work in isolation. DIP tells us     *)
+(*  that every dependency in the design should target an interface or an      *)
+(*  abstract class. Furthermore, a dependency should not target a concrete    *)
+(*  class. It's also worth noting that {e Dependency Injection} is just a     *)
+(*  vehicle to achieve the inversion of control.                              *)
+(*                                                                            *)
+(******************************************************************************)
+
+module LowLevelModule = struct
+  let do_something () = print_endline "LLM Doing something..."
+end
+
+module HighLevelModule = struct
+  (** [LowLevelSubModule] is tightly coupled with the high-level module.
+      This breaks the DIP and should be abstracted with a functor instead. *)
+  module LowLevelSubModule = LowLevelModule
+
+  let say_hello () =
+    print_endline "Hello from HLM, submodule does something:";
+    LowLevelModule.do_something ()
+  ;;
+end
+
+let _ = HighLevelModule.say_hello ()
+
+module type AbstractModule = sig
+  val do_something : unit -> unit
+end
+
+module ConcreteModule : AbstractModule = struct
+  let do_something () = print_endline "ConcreteModule does something..."
+end
+
+module DIP_HLM_Functor (AM : AbstractModule) : sig
+  val say_hello : unit -> unit
+end = struct
+  (** [ASM] is an injected dependency module that implements the
+      [AbstractModule] pseudointerface.*)
+  module ASM = AM
+
+  let say_hello () =
+    print_endline "Hello from a DIP-complied HLM!";
+    print_endline "The abstract submodule does something:";
+    ASM.do_something ()
+  ;;
+end
+
+module DIP_Compliant = DIP_HLM_Functor (ConcreteModule)
+
+let _ =
+  print_newline ();
+  (* Sealing [DIP_Compliant] with a module signature allows us to make the
+     abstract submodule (dependency) private, just like in OOP. *)
+  DIP_Compliant.say_hello ()
+;;
+
+(* Here's how it's done with classes in OCaml. *)
+
+class type abstraction = object
+  method operation : unit
+end
+
+class low_level_class : abstraction =
+  object
+    method operation = print_endline "Low-level class operation/method"
+  end
+
+class high_level_class (dependency' : abstraction) =
+  object
+    val dependency = dependency'
+
+    method use_dependency =
+      print_endline "High level class uses its injected dependency:";
+      dependency#operation
+  end
+
+let _ =
+  let hlo = new high_level_class (new low_level_class) in
+  print_newline ();
+  hlo#use_dependency
+;;
+
+(*
+   DIFICULTAD EXTRA (opcional):
+   Crea un sistema de notificaciones.
+   Requisitos:
+   1. El sistema puede enviar Email, PUSH y SMS (implementaciones específicas).
+   2. El sistema de notificaciones no puede depender de las implementaciones específicas.
+   Instrucciones:
+   1. Crea la interfaz o clase abstracta.
+   2. Desarrolla las implementaciones específicas.
+   3. Crea el sistema de notificaciones usando el DIP.
+   3. Desarrolla un código que compruebe que se cumple el principio.
+*)
+
+module type Notifier = sig
+  val id : string
+  val notify : string -> string -> unit
+end
+
+module EmailService : Notifier = struct
+  let address = "[email protected]"
+  let id = "EMAILER"
+
+  let notify msg destination =
+    print_endline "Email sent:\n--------------------------";
+    printf "From: %s\n" address;
+    printf "To: %s\n" destination;
+    print_endline msg
+  ;;
+end
+
+module NotificationManager (N : Notifier) : sig
+  val create_and_send : string -> string -> unit
+end = struct
+  module NotificationService = N
+
+  let create_and_send msg destination =
+    printf
+      "Sending [%s] to [%s] via %s...\n"
+      msg
+      destination
+      NotificationService.id;
+    NotificationService.notify msg destination
+  ;;
+end
+
+(* We can inject an existing module that satisfies the interface: *)
+module EmailNotificationManager = NotificationManager (EmailService)
+
+(* OR... we can  also inject anonymous modules in-line: *)
+module SMSNotificationManager = NotificationManager (struct
+    let id = "TelcelSMS"
+    let phone_number = "664-563-7778"
+
+    let notify msg destination =
+      print_endline "SMS sent:\n--------------------------";
+      printf "To: [[ %s ]]\n" destination;
+      printf "Text message: %s\n" msg;
+      printf "From: [[ %s ]]\n" phone_number
+    ;;
+  end)
+
+module UbuntuNotificationCenter = NotificationManager (struct
+    let id = "UbuntuNotifications"
+
+    let notify msg destination =
+      printf "Application: %s\n" destination;
+      print_endline msg
+    ;;
+  end)
+
+let _ =
+  print_newline ();
+  EmailNotificationManager.create_and_send
+    "Hello, how are you? Let's meet soon"
+    "[email protected]";
+  print_newline ();
+  SMSNotificationManager.create_and_send "Did you buy milk?" "664-121-4442";
+  print_newline ();
+  UbuntuNotificationCenter.create_and_send
+    "Currently playing: Los Lobos - La Bamba"
+    "Spotify"
+;;